Recuperative coke oven

ABSTRACT

A recuperative coke oven having chambers, each of which is located between two heating walls containing flues in groups communicating for heat exchange between a low calorie gas and/or air and the combustion gas. The flue groups are disposed across the width of the heating walls. The ascending flues are located adjacent the neighboring chambers, and each group of flues is associated with a recuperator containing cells for a low calorie gas and/or air and combustion gas. Flow control means which can be simultaneously but independently operated are provided for each cell.

United States Patent 11 1 Flockenhaus et al.

[ Nov. 19, 1974 [5 RECUPERATIVE COKE OVEN 1,919,098 7/1933 Duckham 202/140 2,863,807 12/1958 Van Ackeren.. 202/142 [75] Inventors: Claus F P Essen'Haarzopfi 3,261,763 7/1966 Tucker 202 142 g g 1 5 Gladbeck; 3,689,365 9 1972 Steding et al. 202 142 urtunt er ec Essen-Bredeney; Heinrich Echterhoff, Essen, all of Germany Primary Examiner--Norman Yudkoff Assistant Examiner-D. Sanders [73] Asslgnees' ai isgiigg gwg Attorney, Agent, or Firm-Wenderoth, Lind & Ponack 9 GmbH, Essen-Kray, both of, Germany 22 Filed: Dec. 29, 1972 [57] ABSTRACT PP 319,471 A recuperative coke oven having chambers, each of which is located between two-heating walls containing [30] Foreign Application Priority Data flues 1n groups communicating for heat exchange between a low calorie gas and/or air and the combustion Dec. 28, 1971 Germany 2164994 g The flue groups are disposed across the width of the heating walls. The ascending flues are located ad- [21 jacem the neighboring chambers and each group of 6 139 flues is associated with a recuperator containing cells 1 earc 202 for a low calorie gas and/0r air and combustion gas. I Flow control means which can be simultaneously but References Cited independently operated are provided for each cell.

UNITED STATES PATENTS Claims, 6 Drawing Figures 516,184 3/1894 Brunck 202/140 d l 2 q $321 14 P E 53 52 2 6& I kf 5 4 of. p 6, F hm l igx gg F': 297 1 51 1 1 1 wi 1 l :2: I 1 9 5 i l 4 Fl L J lk\ RECUPERATIVE COKE OVEN BACKGROUND OF THE INVENTION 7 The invention relates to a recuperative coke oven in which each chamber is located between two heating walls containing flues in groups communicating for heat exchange between a low calorie gas, e.g. blast furnace gas, and/or air and the combustion gas, e.g. coal gas, with recuperator cells disposed below the oven chambers and the heating walls.

Ovens of such kind have already been described, for

heat should be cut down to enable the temperature grainstance in German Patent Specification No. 959,726.

In principle they have the advantage over regenerative coke ovens that the flow reversing devices and their control means can be dispensed with, since the gases always pass through the flues in the same direction. On the other hand recuperators which may be of ceramic or metal construction more easily develop leaks because the partitions between the flowing media must be thin to ensure a satisfactory transfer of heat. Any leak that may occur not only impairs the heating of the chambers but also creates an explosion hazard. Therefore, and due to its low efficiency of heat recovery, the simpler recuperative system has continued to the present day to find little acceptance in the design of coke ovens.

The usual method of coking bituminous coal avails itself of horizontal ehamberovens provided with regenerators for the recovery of heat from the tire gases. In such ovens a plurality of oven chambers flanked by heating walls is combined in a block. The heating walls which are heated by a mixture of burning gas and air principally consist of a plurality of flues combined in groups of which alternately one half is fired, whereas 'the other half serves to carry the outgoing gases. Ac-

cording to the change-over between the fired and unfired flues air of a high calorie gas (high calorie gas heating) or air and a low calorie gas or the fire gas (low calorie has heating) are passed alternately through regenerator cells located underneath the oven chambers.

dient within the charge from the heating wall to the middle of the chamber to level out.

The independent separate supply of heat to each oven chamber is described by the term programmed heating. This permits the quantity of heat that is necessary at any particular time during thecoking process of the charge in each chamber to be supplied and the further supply of heat stopped when this process has been completed.

A coke oven designed for programmed heating is described in the published specification of German Patent Application'No. 2,011 26l/l0a 5/01. Each oven chamber in the oven there described, which works on the regenerative principle, has aleft and right hand heating wall associated with two regenerators which are located below the walls and through which air and gas flow in alternation. In this oven ascending and descending flues alternate in .the longitudinal direction of the chamber. Consequently the surface of each heating wall facing the chamber has areas where the heat flux is less, namely in the region of the unfired flues. The

The general aim in the construction of coke ovens is to raise the flow through rate. The efforts that have been made for achieving this aim have included a diversity of proposals ranging from ways and means to make the coking coal uniform to the employment of particular types of bricks for the heating wallsand the application of particular methods of heating and of control systems for more effectively adapting the heat supply to the heat requirements of the oven chamber and its contents (its charge).

It will be understood that uniform and even cooking of the chamber charge depends particularly upon the controllability of the heat flux through the heating walls. The control means hitherto used consists in a flow control system for metering the rate of flow of the media involved (gas, air and outgoing gas), in providing in alternation ascending and descending individual or groups of flues along the length of the chamber and in feeding several flames at different levels along the length of a flue.

A drawback of the regenerative system is that the lower heat flux from the unfired flues results in the development of areas of the heating wall through which the transfer of heat to the chamber charge is reduced. Moreover, each heating wall participates in heating two a correct balance between thermal demand and supply cannot therefore be provided. Moreover, the provision of two heating walls for each oven chamber is an extravagant and hence costly arrangement.

SUMMARY OF THE INVENTION According to the invention this is achieved by disposing the groups of flues across the width of the heating walls, the ascending flues being located adjacent the neighboring chambers, and by associating each group of flues with a recuperator containing cells for a low calorie gas and/or air and combustion gas and provided with flow control means which can be simultaneously but independently operated. In this arrangement the sides of the heating walls facing the interior of an oven chamber will all be backed by ascending so that the heat flux through the walls can be everywhere controlled to comply optimally with the progress of coking by appropriately setting the control means of the recuperators. There is only one heating wall for two oven chambers. The heating effect of each outside surface of a heating wall can be independently controlled, permitting an oven chamber to be supplied with the same amount of heat on each side although this heat is transferred through two different walls.

In a preferred embodiment of the hunting wall vm-h group of flues comprises a descending l'lue flanked by -two ascending flues adjacent the neighboring oven chambers. This form of construction is simple and inex pensive. It is nevertheless possible to provide two descending flues between the two ascending flues and thus to associate a separate descending flue with each ascending flue. Occasionally it may be preferred to strengthen the heating walls by the provision of a continuous load-bearing wall in the longitudinal centre line of the row of descending flues.

According to another feature of the invention the recuperators may directly adjoin the bottom end of the flue groups and low calorie gas and/or air and combustion gas cells may be disposed in the vertical downward continuation of the corresponding air and gas shafts in the flue groups. The necessity of providing expensive communicating ducts between the flues and the recuperators is thus avoided. The control means for the outgoing gas, for air and a low calorie gas may be located at the free cold end of the recuperators where they are readily accessible in case of need.

Preferably metal recuperators will be employed and located below the oven chambers and heating walls in the loadbearing brickwork so that they can be removed. Modern metal recuperators are sufficiently functionally reliable and their efficiency is sufficient for all practical needs. The hazards once associated with the recuperative recovery of heat, which had in the past deterred persons skilled in the art from using other than regenerative ovens are no longer present, particularly bearing in mind that the recuperators associated with each group of flues are of a size that can be conveniently handled and permit ready replacement whenever this may be necessary. Moreover, it is always possible to design the recuperator or one heating wall so that it can be divided into several parts.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be hereinafter more particularly described with reference to the accompanying drawings in which FIG. 1 is a fragmentary cross-section of the oven chambers and the heating walls of a coke oven heated with a high calorie gas;

FIG. 2 is a section taken on the line l-I in FIG. 1;

FIG. 3a is a sketch illustrating the principle of operation of a recuperator for an oven according to FIGS. 1 and 2;

FIG. 3b is a cross-sectional view taken along lines Illb-Illb of FIG. 3a.

FIG. 4 is a fragmentary cross-section similar to that in FIG. 1, but of a modification of the present invention, and

FIG. 5 is a section taken on the line II-ll in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION In the embodiment illustrated in FIGS. 1 and 2, oven chambers 1 are separated by heating walls 2 divided by cross walls 3 into groups of flues each comprising three flues 4, 5 and 6 placed side-by-side in a direction normal to the main longitudinal axis of the oven chambers. The flues 5 in the center contain no internal elements, but the two flues 4 and 6 which are each adjacent an oven chamber contain air shafts 7 and 9, a bottom air entry 8 and an entry nozzle 10 for a high calorie gas which is likewise at floor level. The two air shafts 7 and 9 end at different levels. The shafts 7 and 9 adjacent the same cross wall 3 in longitudinally consecutive flues 4 and 6, respectively, may be of the same length.

Each group of flues 4 to 6 is associated with a recuperator 16 which is provided directly below the flues in the load-bearing brickwork 17 of the coke oven, and which thus forms a type of downward extension of the two groups of flues 4 to 6. The recuperator consists of two parts 18 which are connected in a manner not shown in the drawings to form a unit. This unit comprises cells 19 to 21 which form the continuation of the air shafts 7 and 9 and of the bottom air entry 8 in the two outer flues 4 and 6, as well as cells 22 which together form a continuation of the flue 5 in the center. At the free end of the recuperator the cells 19 to 22 are provided with control valves 23 to 26 which permit the rate of flow through the cells to be controlled. Located near the control valves 23 to 26 are the control valves 27 for the high calorie gas nozzles 10 in the outer flues 4 and 6.

Referring to FIG. 2, for heating an oven chamber 1 the rows of flues 4 in the heating walls 2 on each side of the chamber 1 cooperate, i.e., the heating program for an entire heating period is controlled by the valves 23 to 27 associated with these flues. The high calorie gas used for heating enters the flues at 10 and burns in stages as it makes contact with the volumes of air entering the flues through the bottom inlet at 8, the medium level end of the air shaft 7 and the high level shaft 9. In this way as well as by means of the ascending continuous flues 4 on the sides of the chamber the heat flux can be adjusted substantially to conform with the requirement of the charge in the chamber.

The fire gases from the ascending heating flues pass through openings 14 and 15 in the walls 11 and 12 into the descending flue 5 in the middle, and then flow through the cells 22 of the recuperator before being discharged through an outlet main 28. These gases flow through the recuperator in a current counter to the air so that there is an intense heat exchange. Heat exchange also takes place in the heating flues because the air shafts 7 and 9 directly adjoin the flue 5 through which the tire gases descend.

FIGS. 4 and 5 illustrate a coke oven which can be operated optionally with a high calorie gas or a low calorie gas (compound coke oven). Moreover, unlike the oven shown in FIGS. 1 to 3 the row of descending flues in the middle is divided by a load-bearing wall 30 resting on the supporting baseplate 31 of the oven. This longitudinal division in practice creates a heating wall 32 containing groups of flues placed crosswise and consisting of two flues 33 and 34 each having a descending flue 35 of its own. Moreover, each flue 33 and 34 has a bottom entry for air 36 and gas 37 as well as an air shaft 38 and a gas shaft 39. Both shafts rise about half way up the flues 33, 34. Moreover, each flue also contains a nozzle 40 for a high calorie gas.

The recuperators 41 and 42 which with reference to FIG. 4 are disposed below the flues 33 and 34 on each side of the bearing wall 30 contain an outgoing gas cell 43 and cells 44 to 47 for entry of air 36, the entry of gas 37, the air shaft 38 and the gas shaft 39. As described with reference to the previous embodiment all the cells are associated with control valves which serve the purposes that have been set forth so that they need not here be further discussed.

When the oven is operated with a low calorie gas the bottoms entries 36 and 37 give rise to a bottom flame, whereas the ends of the shafts 38 and 39 sustain an upper level flame. The combustion gases from each ascending flue 33 and 34 are withdrawn through the descending flue 35, the outgoing gas cell 43 in the recuperator and into an exhaust gas main 48.

When the oven is heated with a high calorie gas the latter enters through the nozzle 40, whereas the entries 36 and 37 as well as the shafts 38 and 39 both conduct air. Again two flames burning at different levels will form in the flues.

What is claimed is:

l. A recuperative coke oven comprising:

a plurality of oven chambers;

heating walls located on opposite sides of each of said oven chambers, each of said heating walls separating adjacent of said oven chambers;

each of said heating walls having therein a plurality of flue groups, said flue groups being aligned in a row extending in the longitudinal direction of therespective heating wall;

each of said flue groups comprising first, second and third separate flues arranged side-by-side across the width of the respective heating wall and in a direction transverse to said longitudinal direction thereof;

said first and second flues of each of said flue groups being ascending flues and being located adjacent the neighboring of said oven chambers separated by the said respective heating wall, and said third flue being a descending flue positioned between said first and second flues;

each of said flue groups having positioned therebelow a recuperator having cells in communication with said flues of said flue group;

separate means connected to each of said cells of each said recuperator for supplying to said recuperator and to the respective said first and second flues a low calorie gas and/or air and for withdrawing from said recuperator and from the respective said third flue a combustion gas; and

separate flow control means operably connected to each of said cells for independently controlling the flow through each of said separate means for sup- I further comprising a separate means for supplying a high calorie gas to each of said first and second flues of each of said flue groups, and separate means for controlling the flow of high calorie gas into each of said separate means for supplying high calorie gas.

4. A recuperative coke oven as claimed in claim 1, wherein each of said first and second flues of each of said flue groups has therein separate air and/or low calorie gas shafts, and said cells of the respective recuperator include separate cells which are vertical continuations of said separate air and/or low calorie gas shafts.

5. A recuperative coke oven as claimed in claim 4, wherein said cells of said respective recuperator further include a cell which is a vertical continuation of said third flue. 

1. A recuperative coke oven comprising: a plurality of oven chambers; heating walls located on opposite sides of each of said oven chambers, each of said heating walls separating adjacent of said oven chambers; each of said heating walls having therein a plurality of flue groups, said flue groups being aligned in a row extending in the longitudinal direction of the respective heating wall; each of said flue groups comprising first, second and third separate flues arranged side-by-side across the width of the respective heating wall and in a direction transverse to said longitudinal direction thereof; said first and second flues of each of said flue groups being ascending flues aNd being located adjacent the neighboring of said oven chambers separated by the said respective heating wall, and said third flue being a descending flue positioned between said first and second flues; each of said flue groups having positioned therebelow a recuperator having cells in communication with said flues of said flue group; separate means connected to each of said cells of each said recuperator for supplying to said recuperator and to the respective said first and second flues a low calorie gas and/or air and for withdrawing from said recuperator and from the respective said third flue a combustion gas; and separate flow control means operably connected to each of said cells for independently controlling the flow through each of said separate means for supplying and withdrawing.
 2. A recuperative coke oven as claimed in claim 1, wherein each of said heating walls further comprises a continuous load-bearing wall extending in said longitudinal direction of the respective said heating wall and centrally dividing said third flue of each of said flue groups.
 3. A recuperative coke oven as claimed in claim 1, further comprising a separate means for supplying a high calorie gas to each of said first and second flues of each of said flue groups, and separate means for controlling the flow of high calorie gas into each of said separate means for supplying high calorie gas.
 4. A recuperative coke oven as claimed in claim 1, wherein each of said first and second flues of each of said flue groups has therein separate air and/or low calorie gas shafts, and said cells of the respective recuperator include separate cells which are vertical continuations of said separate air and/or low calorie gas shafts.
 5. A recuperative coke oven as claimed in claim 4, wherein said cells of said respective recuperator further include a cell which is a vertical continuation of said third flue. 